Control valve for a hydraulic apparatus



June 12, 1956 o. NUBLING 2,749,843

CONTROL VALVE FOR A HYDRAULIC APPARATUS f Filed Aug. 12, 1954 4Sheets-Sheet l A F m U E '0 Z I" ll 0 0 N N H 9 l ll l I June 12, 1956UB 1 2,749,843

CONTROL VALVE FOR A HYDRAULIC APPARATUS Filed Aug. 12, 1954 4Sheets-Sheet 2 24 n b I4 a 20 June 12, 1956 o. NUBLING 2,749,843

CONTROL VALVE FOR A HYDRAULIC APPARATUS Filed Aug. 12, 1954 4Sheets-Sheet 3 June 12, 1956 o. NUBLING ,7

CONTROL VALVE FOR A HYDRAULIC APPARATUS Filed Aug. 12, 1954 4Sheets-Sheet 4 United States Patent C CQNTROL VALVE FOR A HYDRAULICAPPARATUS Otto Niibling, Weener (Ems), Landsburg, Germany ApplicationAugust 12, 1954, Serial No. 449,364

Claims priority, application Germany August 13, 1953 Claims. (Cl.103-41) The present invention relates to a control valve for hydraulicgear pumps and engines, and more particularly to a control valveprovided with a passage preventing excessive pressure in a chambercovered by the sealing face of the control valve.

It is an object of the present invention to provide a control valve forhydraulic gear pumps and engines which permits adjustment of the outputof the hydraulic apparatus.

It is another object of the present invention to provide a channel in acontrol valve for a gear pump by which excessive pressure in a chamberof the gear pump covered by a sealing face of the control valve isprevented.

It is a further object of the present invention to provide a sealingface of the control valve having an increased width whereby undesiredcommunication between pressure and discharge side of the gear pump isprevented in intermediate positions of the control valve.

The present control valve is to be applied to a hydraulic apparatussubstantially described in my Patent No. 2,688,927, dated September 14,1954, and my Patent No. 2,694,288, dated November 16, 1954.

The hydraulic apparatus as particularly described in the said firstmentioned patent comprises a casing, a hollow inner member rotatablymounted in the casing and having teeth on its perimeter defining aplurality of depressed portions thereon, the hollow inner member havingan inner chamber bounded by a cylindrical surface and being formed witha plurality of radially extending conduits connecting each of thedepressed portions with the inner chamber in the hollow inner member andforming slots in the inner cylindrical surface, and an annular outermember rotatably mounted in the casing eccentrically with respect to thehollow inner member and surrounding the same, the outer annular memberhaving a plurality of inner teeth defining depressed portions on itsinner surface and meshing with the teeth on the hollow inner memberwhereby the depressed portions of the inner and outer members formchambers successively increasing in volume on one side of the hollowinner member and decreasing in volume on the other side of the hollowinner member during each revolution and in combination therewith atubular control valve, turnably mounted in the casing extending into theinner chamber in the hollow inner member tightly fitting thereinturnably with respect to the same between two positions normal to eachother, the tubular control valve including an inner transversal walllocated in the region of the conduits and dividing the interior of thetubular control valve into two tubular sections, each tubular sectionformed with an opening in the region of the conduits for supplying anddischarging, respectively, a liquid to the conduits, the innertransversal Wall having diametrically arranged free edge portionsextending substantially parallel to the axis of the tubular controlvalve and provided with diametrically located sealing faces flush withthe outer surface of the tubular control valve, separating the openingsin the two tubular sections and permanently Patented June 12, 1956abutting against the cylindrical inner surface of the hollow innermember in the region of the conduits, the sealing faces adapted to coveropposite slots formed in the inner cylindrical surface by oppositeconduits, the transversal wall being formed with an internal channelterminating in the sealing faces and adapted to establish communicationbetween two opposite chambers, the internal channel forming in thesealing faces narrow slots extending in axial direction of the hollowinner member for substantially the same distances as the slots formed bythe conduits in the inner cylindrical surface of the hollow inner memberso as to permit liquid to flow from a chamber decreasing in volume to anopposite chamber increasing in volume while the sealing faces of thetransversal wall cover the conduits corresponding to the last-mentionedchambers whereby excessive pressure in the last-mentioned chamberdecreasing in volume is prevented.

Excessive pressure in a chamber decreasing in size whose correspondingconduit is covered by a sealing face is prevented by the internalchannel which permits a communication of the closed pressure chamberwith the opposite suction chamber.

With these and other objects in view which will become apparent in thefollowing detailed specification, the present invention will be clearlyunderstood by reference to the accompanying drawings, in which:

Figure 1 shows in longitudinal section a regulable hydraulic apparatusaccording to the present invention e. g. a pump with toothed wheelsarranged one in the other.

Figs. 2 to 6 are cross sections according to line A-B of Fig. l atdifferent positions of the toothed wheels.

Referring now to the drawings, the hydraulic apparatus working as a pumpcomprises essentially an outer member 6 with internal teeth 6 and ameshing inner member 2 with external teeth 2. The outer member 6possesses one tooth more than the inner member 2. The outer member 6rests freely rotatably in the bearings 7 and 8 of the casing 5 whichencloses the gear. The inner member 2 is formed as a cylindrical hollowbody which rests in the bearings 3 and 4 and has on the one side a shaftend portion 1 to which driving means may be connected. The two members 2and 6 are mounted eccentrically with respect to each other and meshing.The distance of the axis of the two wheels is denoted with E (Fig. 2).

In the interior of the cylindrical hollow body of the inner member 2 isarranged a tubular control valve 11. It may be regulated by turning alever 12 mounted thereon. The control valve 11 is divided by a wall intoan inlet chamber 13 and an outlet chamber 17. From the inlet conduit 9 aliquid may enter into the inlet chamber 13 through the ports 10 providedin the cylindrical hollow body, whilst the discharge of the liquid fromthe outlet chamber 1'7 of the control valve 11 takes place through theports 18 into the outlet conduit 19.

The inner member 2 has conduits 14 or 16 traversing it radially from theinterior to the outer surface. Through these conduits liquid may flowfrom or to the control valve 11. The liquid flowing from the interior ofthe control valve 11 to the exterior of the member 2 enters the Workingchambers 15 which are defined between the inner and outer members 2 and6.

In Figs. 2 to 6 different positions of the control valve 11 are shown inrelation to the members 2 and 6. During the rotation of the members 2and 6 in the direction of the arrow (Figs. 2 to 6), the chambers 20defined between two opposite teeth increase on one side whilst thechambers 21 defined between the teeth of the two members decrease on theother side. Therefore, the suction chambers 20 draw liquid through theconduits 14 3. whilst within the pressure chambers 21 liquid flows outthrough the conduits 16. The quantity of liquid pressed out from thechamber 22 corresponds with the quantity of liquid sucked into thechamber 23 (Fig. 2). Accordingly only the chambers 24 feed liquid intothe outlet chamber 17 and outlet pipe 19. The quantity of liquid pressedout from the chamber 25 corresponds with the quantity of liquid suckedinto the chamber 26. Correspondingly only the chamber 27 sucks fluidfrom the interior of the control valve 11. According to the turning ofthe control valve 11 the quantity of liquid sucked off changes.

In accordance with the present invention, the controlling sealing facenamely the part of the control valve 11, which engages directly theinterior surface of the inner member 2 and is bounded by controllingsealing faces, is wider on the pressure-side than on the suction side.

In Fig. 2 the controlling sealing face of the control valve 11 indirection to the pressure-side is smaller for the distance a than thewidth b of the conduits 14 or 16. This means, that the conduit 28 (Fig.3) will never be completely closed during the rotation of the member 2from the position shown in Fig. 2 to that shown in Fig. 3.

In the position shown in Fig. 3 the transversal channel 29 in the wallof the rotatory valve 11 is opened for the distance a, when thecontrolling sealing face 31 disposed in the rear of the direction ofrotation just closes the conduit 28. This arrangement brings about thatin the diminishing chamber 31 an intolerable over-pressure can neverarise. During further rotating movement the liquid pressed out from thechamber 31 is fed through the transversal channel 29 into the chamber32, thereby preventing the formation of a vacuum in the chamber 32.

In the position shown in Fig. 4 the members 2 and 6 are still furthermoved. On the suction side the width of the sealing face is exactly thesame as the width b of the conduit 35. In this case the chamber 15 iscompletely closed. Yet the formation of a vacuum in the chamber 15 isnot possible because the liquid pressed out from the chamber 31 is fedthrough the transversal channel 29 into the chamber 15. Therefore, inaccordance with the invention, the distance d of engagement between thesealing face of the rear end of the dividing wall of the control valve11 and the inner face of the inner member 2 corresponds with the widthof the transversal channel 2 minus the distance a.

Fig. shows the further course of the controlling process performed bythe control valve 11. The diminishing pressure chamber 31 presses liquidduring rotation of the members from the position shown in Fig. 4 to theposition shown in Fig. 5 through the transversal channel 29 into thesuction chamber 15. Since the conduit 33 gets into communication duringthis movement with the pressure-side 34 of the control valve 11 thechamber will be at least partly filled with liquid.

During the further rotation of the members 2 and 6 to the position shownin Fig. 6 of the controlling sealing face of the control valve 11disposed in front of the direction of rotation opens the diminishingpressure chamber 31 to the outlet chamber 17 of the control valve 11, sothat the liquid pressed out from the chamber 31 is fed to the outletchamber 17 on the suction side. Simultaneously the transversal channel29 is gradually closed to the side of the enlarging suction chamber. Itmay be seen, that the distance 1 in Fig. 4 corresponds with the distanceg of the transversal channel 29 from the conduit 35 minus the distancea.

By arrangement of the sealing faces of the control valve 11 inaccordance with the distances set forth above, an inadmissible rise ofthe pressure in the pressure chamher and the formation of a vacuum inthe suction chamber is at all times avoided. During rotation of themembers 2 and 6 from the position shown in Fig. 2 to that .4 shown inFig. 3 and from the position shown in Fig. 5 to that shown in Fig. 6 acommunication between the suction-side and the pressure side in the pumpis brought about, which is equal to null in the position shown in Fig.2, continually increases up to the maximal value of a/ 2 and decreasesto null in the position shown in Fig. 3. The direct communicationbetween the suction-side and the pressure-side is, however, of nodamaging effect in fast running pumps, because the moment of inertia ofthe liquid prevents the flow of a nominal quantity of fluid from thepressure-side to the suction-side.

The manner of using and applying the embodiment of my invention setforth above will be clear from the foregoing description. It is, ofcourse, to be understood that my invention is not limited to thespecific embodiment thereof here shown and described for purposes ofillustration only. Various changes and modifications may be made in thehydraulic apparatus set forth and in the structural details shown,without departing from the spirit of this invention.

While I have disclosed one embodiment of the present invention, it is tobe understood that this embodiment is given by example only and not in alimiting sense, the

scope of the present invention being determined by the objects and theclaims.

I claim:

1. in a hydraulic apparatus including a casing, a hollow inner memberrotatably mounted in said casing and having teeth on its perimeterdefining a plurality of depressed portions thereon, said hollow innermember having an inner chamber bounded by a cylindrical surface andbeing formed with a plurality of radially extending conduits connectingeach of said depressed portions with said inner chamber in said hollowinner member and forming slots in said inner cylindrical surface, and anannular outer member rotatably mounted in said casing eccentrically withrespect to said hollow inner member and surrounding the same, said outerannular member having a plurality of inner teeth defining depressedportions on its inner surface and meshing with said teeth on said hollowinner member whereby said depressed portions of said inner and outermembers form chambers successively increasing in volume on one side ofsaid hollow inner member and decreasing in volume on the other side ofsaid hollow inner member during each revolution, in combination, atubular control valve turnably mounted in said casing extending intosaid inner chamber in said hollow inner member tightly fitting therein,said tubular control valve including an inner transversal well locatedin the region of said conduits and dividing said tubular control valveinto two tubular sections, each tubular section formed with an openingin the region of said conduits for supplying and discharging,respectively, a liquid to said conduits, each opening extending fornearly half of the periphery of said tubular control valve opposite theopening in the other of said two tubular sections, said openings beinglocated on opposite sides of said inner transversal wall, said innertransversal wall having diametrically arranged free edge portionsextending substantially parallel to the axis of said tubular controlvalve and provided with diametrically located sealing faces flush withthe outer surface of said tubular control valve, separating saidopenings in said two tubular sections and permanently abutting againstsaid cylindrical inner surface of said hollow inner member in the regionof said conduits, said sealing faces adapted to cover opposite conduitsduring rotation of said inner and outer members, said transversal wellbeing formed with an internal channel terminating in said sealing facesand adapted to establish communication between a contracting and anexpanding chamber when said sealing faces cover the conduits associatedwith said last mentioned chambers, one of the said sealing faces beinglocated during turning of said tubular control valve on the side of saidhollow inner member on which chambers of increasing volume are formed,and the other of said sealing faces being located during turning of saidtubular control valve on the side of said hollow inner member on whichchambers of decreasing volume are formed, said one of said sealing faceshaving substantially the same width as said slots formed in saidcylindrical surface by said conduits, and said other of said sealingfaces having a width greater than the width of said slots formed in saidcylindrical surface by said conduits.

2. The hydraulic apparatus, as set forth in claim 1, in which saidsealing face of greater width is enlarged over the width of said slotsformed in said cylindrical surface by said conduits in the direction ofrotation for a distance not larger than the distance of the forward edgeof said internal channel of the transversal wall from the rear edge ofthe slot in said hollow inner mem' ber associated with the correspondingopposite sealing face having substantially the same width as said slotsformed in said cylindrical surface by said conduits, in the position inwhich said slot on the side of said hollow inner member, on whichchambers of increasing volume are formed, has just been closed.

3. The hydraulic apparatus, as set forth in claim 1, in which saidsealing face of greater width is enlarged over the width of said slotsformed in said cylindrical surface by said conduits in the directionopposite to that of rotation for a distance not larger than the distanceof the rear edge of said internal channel of the transversal wall fromthe forward edge of said slot, formed in said cylindrical surface bysaid conduits, in direction of rotation on the side of said hollow innermember on which chambers of decreasing volume are formed, in theposition in which said slot on the side of said hollow inner member, onwhich chambers of increasing volume are formed, has just been closed' 4.The hydraulic apparatus, as set forth in claim 1, in which said sealingface of greater width is enlarged over the width of said slots formed insaid cylindrical surface by said conduits in the direction of rotationfor a distance not larger than the distance of the forward edge of saidinternal channel of the transversal wall from the rear edge of the slotof said hollow inner member associated with the corresponding oppositesealing face having substantially the same width as said slots formed insaid cylindrical surface by said conduits, in the position in which saidslot on the side of said hollow inner member, on which chambers ofincreasing volume are formed, has just been closed, and in which saidsealing face of greater width is enlarged over the Width of said slotsformed in said cylindrical surface by said conduits in the directionopposite to that of rotation for a distance not larger than the distanceof the rear edge of said internal channel of the transversal wall fromthe forward edge of said slot, formed in said cylindrical surface bysaid conduits, in direction of rotation on the side of said hollow innermember on which chambers of decreasing volume are formed, in theposition in which said slot on the side of said hollow inner member, onwhich chambers of increasing volume are formed, has just been closed.

5. The hydraulic apparatus, as set forth in claim 1, in which theenlargements in and opposite to the direction of rotation, respectively,of the said sealing face on the side of the said hollow inner member onwhich chambers of decreasing volume are formed over the width of thesaid slots formed in said cylindrical surface by said conduits are equalto the distance of the forward edge of said internal channel of thetransversal Wall from the rear face of the latter in the position inwhich said slot on the side of said hollow inner member, on whichchambers of increasing volume are formed, has just been closed, and tothe width of said internal channel taken in the direction of a planeperpendicularly to the rotating axis of said control valve,respectively, said last mentioned distance and said last mentioned widthbeing shortened for an amount which is equal to the width of a slotformed between the rear edge of the said sealing face in direc tion ofrotation on the side of said hollow inner member on which chambers ofdecreasing volume are formed and the rear edge of said slot formed insaid cylindrical surface by said conduits, in the position in which therear edge of the said internal channel coincides with the front edge ofsaid slot formed in said cylindrical surface by said conduits, the saidamount being dependent upon the number of revolutions of said inner andouter members.

References Cited in the file of this patent UNITED STATES PATENTS1,341,846 Gollings June 1, 1920 2,011,338 Hill Aug. 13, 1935 2,140,966Nichols Dec. 20, 1938 2,688,927 Nuebling Sept. 14, 1954 2,694,288Nuebling Nov. 16, 1954 FOREIGN PATENTS 9,359 Great Britain of 1915

